CN102075474A - Channel state tracking method based on training sequence - Google Patents
Channel state tracking method based on training sequence Download PDFInfo
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- CN102075474A CN102075474A CN2009102018390A CN200910201839A CN102075474A CN 102075474 A CN102075474 A CN 102075474A CN 2009102018390 A CN2009102018390 A CN 2009102018390A CN 200910201839 A CN200910201839 A CN 200910201839A CN 102075474 A CN102075474 A CN 102075474A
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Abstract
The present invention discloses a channel state tracking method based on a training sequence, wherein the method is suitable for an OFDM system and comprises the steps of: (1) obtaining channel impulse response information according to a known training sequence; (2) determining a decision parameter according to the channel impulse response information, wherein the decision parameter is used for characterizing the channel characteristic; and (3) deciding the current channel type from a plurality of channel types supposed beforehand according to the decision parameter. By adopting the channel state tracking method based on a training sequence, an OFDM receiver has the capability of tracking channel change in mobile reception environment, and can correspondingly adjust the channel estimating method according to the channel change, thereby ensuring that the receiver can work in a better working state under a plurality of channel environments. The channel state tracking method based on a training sequence of the invention is especially suitable for a wireless communication system designed for reception in the mobile environment.
Description
Technical field
The present invention relates to the transmission of wireless signals field, particularly relate to a kind of wireless communication system that is applied to, based on the channel status tracking of training sequence.
Background technology
In wireless communication system, transmit in communication process, the direct signal on straight line path, the reflection that also can experience one or more reflecting objects usually arrives receiver through different propagation paths afterwards.These all have nothing in common with each other through its signal amplitude of signal and phase places of different propagated, and reach after the receiver with the small time difference, interfere the fluctuation that causes received signal intensity mutually, cause distorted signals.The multipath effect of radio propagation channel that Here it is.Multipath effect usually prolongs the time of the arrival receiver that transmits.The common moment that arrives receiver with first detectable signal arrives the moment of receiver as terminal point, the maximum delay that is defined as propagation channel relative time delay between the two as the reference point with last detectable signal.Between first detectable signal and last detectable signal, equally also exist the detectable signal that have nothing in common with each other a plurality of relative time delays.The detectable signal that these time delays have nothing in common with each other is propagated via the multipath component that amplitude and phase place have nothing in common with each other respectively.The time delay of these multipath components, power distribution characteristics are commonly referred to the power delay profile of wireless channel, are also referred to as the pusle response characteristics of wireless channel.
From frequency spectrum, these multipath components can cause on different frequency components, and the response of the amplitude/phase of channel has nothing in common with each other.Usually weigh amplitude/phase response relation between this different frequency with the size of parameter correlation bandwidth.Correlation bandwidth is meant in the particular frequency range that two frequency components have very strong amplitude/phase correlation.Can think that in correlation bandwidth all spectrum components all pass through with much at one gain and linear phase.Therefore concerning transmission signals,, drop in the correlation bandwidth of channel, can think that the signal on the different frequency component has all experienced identical channel fading influence if its signal bandwidth is very narrow; If instead signal bandwidth is much larger than the correlation bandwidth of channel, the signal on the different frequency component will experience different channel fading influences so, and this phenomenon is called the frequency selective fading of signal, and corresponding propagation channel is called frequency-selective channel.The power delay profile of the big or small cochannel of the correlated bandwidth of channel has deterministic relation.The power delay profile characteristic generation conversion of channel, its pairing channel frequency response characteristic will change.The channel coherence bandwidth that different power delay profile is corresponding different, the propagation channel that becomes during therefore for one, its channel impulse response is not invariable, and the channel fading influence that suffers on frequency of transmitting signal also just is in the continuous variation so.
Concerning receiver, from the received signal of experience channel fading influence, correctly recover and transmit the just necessary adverse effect of eliminating propagation channel.Therefore concerning various wireless communication system, channel estimation technique all is one of technology of most critical.In recent years, OFDM (OrthogonalFrequency Division Multiplexing, OFDM) technology is widely used in the Wireless Broadband Communication Systems.Significant advantage of OFDM technology is exactly to be divided into a plurality of parallel subcarriers to the carrier wave of a relative broad, the bandwidth of each subcarrier is much smaller than the correlation bandwidth of channel, therefore concerning each sub-carrier signal, the channel frequency decline that it experienced all is smooth.This has just overcome the adverse effect of selectivity of channel frequency decline.If channel estimation technique can obtain the channel frequency response characteristic on the different sub carrier, receiver just can be realized coherent demodulation, thereby correct recovering transmits.
A kind of practices well of obtaining the channel frequency response characteristic is to insert certain pilot tone signal in transmitting.The frequency response that receiving terminal obtains on the pilot sub-carrier by known pilot signal estimates that if in the whole signal bandwidth all be known pilot signal, receiver just can obtain the frequency domain response estimation of channel on whole signal bandwidth so.Another kind of way commonly used is the pilot distribution pattern according to prior agreement, insertion pilot signal at interval transmits on frequency domain, the frequency response that receiver estimates earlier on the pilot sub-carrier is estimated, and then the correlation by frequency response characteristic between the adjacent sub-carrier, estimate channel frequency response on other subcarriers by the method for interpolation.Concerning receiver, in order to reach the purpose that preferred channels is estimated, usually all be the coefficient that designs the method and the interpolation of interpolation according to the channel power delay character of prior supposition, the coefficient of the method for these interpolation and interpolation all is changeless usually in receiving course.This method is normally effective for the unconspicuous propagation channel of conversion.But for the bigger mobile system of conversion, the normally conversion of its propagation channel along with the conversion of surrounding environment, in a single day the channel power delay character changes, will make that predefined interpolation method and interplotation system are not optimum under some environment, thereby reduced accuracy of channel estimation, and then influenced the receptivity of receiver.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of channel status tracking based on training sequence, makes the OFDM receiver have the ability of track channel change under mobile reception environment, can adjust channel estimation methods relatively according to channel variation.
For solving the problems of the technologies described above, the channel status tracking based on training sequence of the present invention is to adopt following technical scheme to realize: obtain channel impulse response information according to known training sequence; Be identified for characterizing the decision parameter of the characteristic of channel according to channel impulse response information; From the multiple channel type of prior supposition, rule out the type of current channel according to described decision parameter.
Adopt the channel status tracking based on training sequence of the present invention, can not increase substantially under the prerequisite of implementation complexity and cost, effectively follow the tracks of receiver channel state variation under the mobile status, self adaptation is adjusted channel estimation methods reasonably and accurately.Can avoid the channel estimation methods and the characteristic of channel not to match causes receptivity low, can prevent that again the too frequent switching of channel estimation methods from causing the receptivity instability, thereby guarantee that receiver can both be operated under the multiple channel circumstance under the more excellent operating state, for subsequent communication channel is estimated to provide convenience.
Description of drawings
The present invention is further detailed explanation below in conjunction with accompanying drawing and embodiment:
Accompanying drawing is method one an embodiment handling process schematic diagram of the present invention.
Embodiment
The characteristic of channel in the mobile radio system comprises multipath transmisstion, time delay expansion, fading characteristic and Doppler effect etc.In conjunction with the accompanying drawings,, will for example describes, comprise the steps: with Chinese digital mobile multi-media broadcasting system (CMMB, China MobileMultimedia Broadcast) in the following embodiments for clearer elaboration the present invention
Step 1, obtain channel impulse response information according to known training sequence.The method of specific implementation is:
A, according to the CMMB protocol definition, all having two length in the beginning of each time slot signal is 2048 synchronizing signal, remove outside the virtual subnet carrier wave, these two synchronizing signals are mapped with 1536 useful signals on subcarrier in frequency domain, described useful signal is to determine known training sequence concerning receiver.Therefore get time-frequency FFT (fast Fourier transform) that arbitrary signal in described two synchronizing signals carries out at 2048 and change and obtain corresponding frequency domain sequence, and to extract length be 1536 received signal sequence.Receiver is got the conjugate of local known training sequence, and multiplies each other in twos with this received signal sequence, obtains the frequency domain training sequence after relevant the processing.
B, IFFT (Fast Fourier Transform Inverse) the conversion when frequency domain training sequence after relevant the processing is carried out 2048 frequency promptly obtain length and are 2048 channel impulse response sequence.
Step 2, be identified for characterizing the decision parameter of the characteristic of channel according to channel impulse response information.The method of specific implementation is:
A, ask the average power content P of channel impulse response sequence
e, most powerful path performance number P
MaxAnd the position I of this most powerful path in sequence
Max
B, according to average power content P
ePerformance number P with most powerful path
MaxObtain multipath detection threshold ξ
1, ξ
1=max (k
1P
e, P
Max/ k
2).Wherein, k
1And k
2Delay character according to propagation channel is configured, and need satisfy k
1And k
2It all is positive number greater than 1.
C, according to multipath detection threshold ξ
1In the channel impulse response sequence, carry out effective diameter identification, promptly select all power greater than multipath detection threshold ξ
1Effective diameter; Find out the first path position I of current time slots multipath in distributing according to described effective diameter
f(n) and the most last path position I
d, finally obtain maximum delay τ and most powerful path time delay τ in the distribution of multipath time delay
Max
D, according to most powerful path performance number P
MaxDetermine strong footpath detection threshold ξ
2,
ξ
2＝P
max/kx，
Wherein, k
3Be the integer greater than 1, its value need guarantee ξ
2＞＞ξ
1Inequality is set up.
E, the strong footpath of basis detection threshold ξ
2In the channel impulse response sequence, carry out the identification of strong footpath, promptly select all power greater than strong footpath detection threshold ξ
2Effective diameter.Thereby determine the position I in last strong footpath in the multipath distribution
s, finally obtain the strong footpath time delay τ in the distribution of multipath time delay
s, τ
s=I
s-I
f
Step 3, from the multiple channel type of prior supposition, rule out the type of current channel according to described decision parameter.The method of specific implementation is:
I, the channel delay of supposing operational environment in advance the most very much not can surpass time delay τ
1=1536 (usually the maximum delay of propagation channel is in tens microsecond magnitudes, and according to the baseband sampling speed of CMMB signal 10MHz, the multipath of propagation channel distributes and is reflected on the base band data probably in a hundreds of sampling point rank, so selects τ here
1=1536 can contain the multipath distribution of whole channel), according to the difference of effective diameter distribution character, (K is an integer, 0＜K＜τ to choose K
1) the individual maximum delay τ that is not more than
1Value as detection threshold η
i, i=1,2 ... K, 0＜η
1＜...＜η
K＜τ
1, a described K threshold value distributes channel delay and is divided into K+1 interval.Respectively most powerful path time delay τ
Max, strong footpath time delay τ
sCompare with K threshold value with maximum delay τ, thereby which time delay interval most powerful path, last strong footpath and the most last footpath of determining current channel are dropped in.
The actual detection threshold that adopts is at prior preset threshold η
iThe basis on, compare the difference of the variation tendency that obtains with historical decision parameter and in certain scope, float according to current decision parameter.If the decision parameter of current time is compared when changing from small to big with the decision parameter of historical juncture, then detection threshold η '
iWith prior preset threshold η
iBe consistent, i.e. η '
i=η
iWhen if the decision parameter of current time is compared from large to small with the decision parameter of historical juncture, detection threshold η ' then
iAt prior preset threshold η
iThe basis on float downward certain side-play amount, i.e. η '
i=η
i-λ, wherein, λ (λ＞0) is a side-play amount.
The difference of the combinations of states in these three intervals that II, basis are determined, respectively from delay multipath channel in short-term, medium time delay multipath channel, long delay multipath channel, etc. strong multipath channel and divide equally the distribution multipath channel and do state matches, find out the consistent maximum channel of state matches, promptly think and the immediate channel type C of current channel.
Receiver is estimated new channel type C ' every the regular hour, and compares with the last historical channel type C.If channel type does not change, then keep current channel estimation methods constant, if channel type changes, then the channel type C ' that obtains according to current estimation adjusts corresponding channel estimation methods.
Because time slot signal length is 25 milliseconds in the CMMB signal, so concerning the CMMB signal, receiver can be the cycle to estimate the once type of current channel with 25 milliseconds.On a same time slot of the current channel type basis that channel type is compared constantly, whether judgement needs to upgrade the channel estimation methods of current time slots, and channel status is followed the tracks of and the purpose of self adaptation adjustment channel estimation methods thereby reach.
More than by specific embodiment the present invention is had been described in detail, but these are not to be construed as limiting the invention, for example the present invention is not limited to the CMMB system, and is applicable to wireless communication systems that all receive in mobile environment.Under the situation that does not break away from the principle of the invention, those skilled in the art also can make many distortion and improvement, and these also should be considered as protection scope of the present invention.
Claims (6)
1. the channel status tracking based on training sequence is characterized in that: comprise the steps: step 1, obtain channel impulse response information according to known training sequence; Step 2, be identified for characterizing the decision parameter of the characteristic of channel according to channel impulse response information; Step 3, from the multiple channel type of prior supposition, rule out the type of current channel according to described decision parameter.
2. method according to claim 1 is characterized in that: step 1 is described to be obtained channel impulse response information according to known training sequence and adopts following method to realize:
Steps A, carry out time-frequency FFT conversion to received signal and obtain frequency domain sequence, get the conjugate of known training sequence, and multiply each other in twos, obtain the frequency domain training sequence after relevant the processing with this frequency domain sequence;
Step B, the IFFT conversion obtained the channel impulse response sequence when frequency domain training sequence after relevant the processing was carried out frequency.
3. method according to claim 1 is characterized in that: the described decision parameter that is identified for characterizing the characteristic of channel according to channel impulse response information of step 2 adopts following method to realize:
Step a, ask the average power content P of channel impulse response sequence
e, most powerful path performance number P
MaxAnd the position I of this most powerful path in sequence
Max
Step b, according to average power content P
ePerformance number P with most powerful path
MaxObtain multipath detection threshold ξ
1, ξ
1=max (k
1P
e, P
Max/ k
2); Wherein, k
1And k
2Delay character according to propagation channel is configured, and k
1And k
2It all is positive number greater than 1;
Step c, according to multipath detection threshold ξ
1In the channel impulse response sequence, carry out effective diameter identification, promptly select all power greater than multipath detection threshold ξ
1Effective diameter, thereby determine the first path position I of multipath in distributing
fThe most last path position I
d, finally obtain maximum delay τ and most powerful path time delay τ in the distribution of multipath time delay
Max,
Steps d, according to most powerful path performance number P
MaxDetermine strong footpath detection threshold ξ
2, ξ
2=P
Max/ k
3, ξ
2＞＞ξ
1Wherein, k
3Be the integer greater than 1, its value need guarantee ξ
2＞＞ξ
1Inequality is set up;
Step e, the strong footpath of basis detection threshold ξ
2In the channel impulse response sequence, carry out the identification of strong footpath, promptly select all power greater than strong footpath detection threshold ξ
2Effective diameter; Determine the position I in last strong footpath in the multipath distribution according to described effective diameter
s, finally obtain the strong footpath time delay τ in the distribution of multipath time delay
s, τ
s=I
s-I
f
4. method according to claim 1 is characterized in that: the described type that rules out current channel according to decision parameter from the multiple channel type of prior supposition of step 3 adopts following method to realize:
Step I, the channel delay of supposing operational environment in advance the most very much not can surpass τ
1,, choose K and be not more than maximum delay τ according to the difference of effective diameter distribution character
1Value as detection threshold η
i, i=1,2 ... K, 0＜η
1＜...＜η
K＜τ
1, a described K threshold value distributes channel delay and is divided into K+1 interval; Respectively according to most powerful path time delay τ
Max, strong footpath time delay τ
sDetermine with the size of maximum delay τ which time delay interval most powerful path, last strong footpath and the most last footpath of current channel drop on;
Step II, different according to the most powerful path of determining, last strong footpath and three time delay intervals, the most last footpath, respectively from delay multipath channel in short-term, medium time delay multipath channel, long delay multipath channel, etc. strong multipath channel and divide equally and find out immediate matching value the distribution multipath channel, be defined as the Type C of current channel.
5. method according to claim 4 is characterized in that: the detection threshold that adopts in step I is at prior preset threshold η
iThe basis on, can compare the difference of the variation tendency that obtains with historical decision parameter and in certain scope, float according to current decision parameter; If the decision parameter of current time is compared when changing from small to big with the decision parameter of historical juncture, then detection threshold η '
iWith prior preset threshold η
iBe consistent, i.e. η '
i=η
iWhen if the decision parameter of current time is compared from large to small with the decision parameter of historical juncture, detection threshold η ' then
iAt prior preset threshold η
iThe basis on float downward certain side-play amount, i.e. η '
i=η
i-λ.
6. method according to claim 4 is characterized in that: receiver is estimated new channel type C ' every the regular hour, and compares with the last historical channel type C; If channel type does not change, then keep current channel estimation methods constant, if channel type changes, then the channel type C ' that obtains according to current estimation adjusts corresponding channel estimation methods.
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| CN113746576A (en) * | 2021-11-03 | 2021-12-03 | 北京交通大学 | Wireless channel recording method, device and medium based on 5G test signal |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1585297A (en) * | 2004-05-26 | 2005-02-23 | 中兴通讯股份有限公司 | Method and device for shaping wave beam form of intellectual antenna |
| CN1835483A (en) * | 2005-12-29 | 2006-09-20 | 上海贝豪通讯电子有限公司 | Channel estimation method in TDSCDMA system compatibility to OFDM tech |
| US7406120B1 (en) * | 2005-04-01 | 2008-07-29 | Bae Systems Information And Electronic Systems Integration Inc. | Transmission channel impulse response estimation using fast algorithms |
| CN101488798A (en) * | 2008-01-14 | 2009-07-22 | 大唐移动通信设备有限公司 | Timing measurement method, system and apparatus |
-
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1585297A (en) * | 2004-05-26 | 2005-02-23 | 中兴通讯股份有限公司 | Method and device for shaping wave beam form of intellectual antenna |
| US7406120B1 (en) * | 2005-04-01 | 2008-07-29 | Bae Systems Information And Electronic Systems Integration Inc. | Transmission channel impulse response estimation using fast algorithms |
| CN1835483A (en) * | 2005-12-29 | 2006-09-20 | 上海贝豪通讯电子有限公司 | Channel estimation method in TDSCDMA system compatibility to OFDM tech |
| CN101488798A (en) * | 2008-01-14 | 2009-07-22 | 大唐移动通信设备有限公司 | Timing measurement method, system and apparatus |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113746576A (en) * | 2021-11-03 | 2021-12-03 | 北京交通大学 | Wireless channel recording method, device and medium based on 5G test signal |
| CN113746576B (en) * | 2021-11-03 | 2022-07-19 | 北京交通大学 | Wireless channel recording method, device and medium based on 5G test signal |
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Effective date of registration: 20151116 Address after: 214072 Jiangsu province Binhu District of Wuxi City Liyuan Development Zone 530 No. 1 building twelve room 1203 Patentee after: JIANGSU MAXSCEND TECHNOLOGY CO., LTD. Address before: 201203, 7 floor, building No. 4, Zhang Jiang microelectronics port, No. 690 blue wave road, Shanghai, Pudong New Area Patentee before: Maxscend Technologies Inc. |
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Address after: 214072 Jiangsu province Binhu District of Wuxi City Liyuan Development Zone 530 No. 1 building twelve room 1203 Patentee after: Jiangsu Zhuo Sheng microelectronics Limited by Share Ltd Address before: 214072 Jiangsu province Binhu District of Wuxi City Liyuan Development Zone 530 No. 1 building twelve room 1203 Patentee before: JIANGSU MAXSCEND TECHNOLOGY CO., LTD. |